API Endpoint

⚠️ Important: RVM Compliance & Sending Guidelines
All Ringless Voicemail (RVM) activity through Drop Cowboy must follow federal and state regulations, including the TCPA and Telemarketing Sales Rule (TSR).
Key compliance requirements:
Obtain explicit consent from all recipients
Provide a clear opt-out mechanism
Use only approved number pools and audio recordings
Note: Drop Cowboy's API supports 1-to-1 RVM sends only — bulk or campaign-style submissions are not supported.
Sending Limits & Delivery Behavior
Soft limit: 10,000 requests per second
Keep concurrent requests under 100 for best performance
Scaling: If you plan to exceed 1,000 requests/sec, contact your Drop Cowboy account manager or support
Contact frequency:
Default: 3 attempts in 3 days (TCPA)
FDCPA-regulated users: up to 7 attempts in 7 days (configurable)
Delivery timing:
Most RVMs deliver within 5 minutes
Messages queued outside 8am–9pm local TCPA hours are automatically held until the next valid window
Call forwarding: Avoid forwarding to toll-free numbers — some carriers block these connections, reducing callback success rates
Compliance Support
Drop Cowboy provides built-in tools and account-level configuration options to help you:
Enforce contact attempt limits
Manage local time compliance
Track consent and opt-out requests
For advanced configurations or higher send volumes, contact Drop Cowboy Support or your account manager.

POST

https://api.dropcowboy.com/v1/rvm

RVM Attributes

Required Body Keys

Name

Type

Description

Required?

team_id

STRING

Located on the API Setting tab.

Example: <Your Account>

YES

secret

STRING

Located on the API Setting tab.

Example: <Your Secret>

YES

brand_id

STRING

Located on in your account's trust center tab.

Example: <Your Brand GUID>

YES

phone_number

STRING

Your contact's phone number in E.164 format.

Example: +15552223333

YES

Conditional Body Keys

Name

Type

Description

Required?

audio_url

STRING

Use of this property requires special approval.

Please contact support.

A URL to the voicemail audio to play (mp3 or wav).

Example: https://example.com/yourfile.mp3

Conditionally, if not using tts_body or recording_id

*Not required if you are using recording_id or voice_id

audio_type

STRING

Use of this property requires special approval.

Please contact support.

The file type of audio_url: mp3 or wav.

Example: mp3

Conditionally, if using audio_url

forwarding_number

STRING

The phone number to forward calls and texts to when the contact replies to your message. Must be in E.164 format.

Example: +15557778888

Conditionally, if not using pool_id or phone_ivr_id

recording_id

STRING

The ID of the audio recording to send to your contacts. Located on in your account's recordings tab.

Example: <Your Recording GUID>

Conditionally, if not using audio_url or tts_body

*Not required if you are using audio_url or voice_id

voice_id

STRING

The ID of the Mimic AI^TM voice to use when reading your tts_body. Located on in your account's voices tab.

Example: <Your Voice GUID> Pro Voice ID’s SSML Compatible female: c42629ad-c6ac-4499-87b4-2e87f3a7fbf7

SSML Compatible

male: 436e221c-b9b8-4825-8fce-5924dc1a2792

Tony dc786997-e027-4986-8d0b-b1efa0c26937 Myra bbf0eb48-2da5-4929-8945-a5920b76b6c1

Conditionally, if using tts_body

*Not required if you are audio_url or recording_id

tts_body

STRING

The text you want Mimic AI^TM to convert to speech using the voice_id you specify.

Example: Hey Joe, this is Bob from Brand. I'm calling you because...

Conditionally, if using voice_id

status_format

STRING

Drop Cowboy supports status code mapping to emulate other platforms' status codes sent to you in the callback_url.

Do not set this value unless instructed by Drop Cowboy to do so.

Conditionally, talk to your Drop Cowboy account manager for a list of available mappings

byoc

OBJECT

Wholesale customers are able to specify SIP Trunks and STIR/SHAKEN credentials.

Please contact us for details.

Conditional if using BYOC SIP trunking

Optional Body Keys

Name

Type

Description

Required?

foreign_id

STRING

A value to identify this drop in your system. Will be passed through to you in the webhook callback. Max length 256 characters.

Example: <Your system's ID>

Optional

privacy

STRING

Caller ID privacy settings. A value of "off" will display a caller ID on your contact's phone so the contact can return your calls. A value of "full" will display "Unknown Caller" on your contact's phone. Defaults to "off".

Example: off

Optional

phone_ivr_id

STRING

The IVR to use when your contact calls you back. Located on in your account's phone IVR tab.

Example: <Your IVR GUID>

Optional, if not using forwarding_number

pool_id

STRING

The ID of the private number pool to select phone numbers from based on geographic location of your contact.

Defaults to the public pool of shared numbers.

Optional

postal_code

STRING

The zip code / postal code of your contact. Supplying a value for postal code is optional but provides more accurate compliance with TCPA calling hours.

Example: 02101 or 90210-0001

Optional, highly recommended

callback_url

STRING

Override the default RVM webhook URL that you specified in your API settings.

Example: http://example.com

Optional, highly recommended

Example Requests

Send ringless voicemail

post

Directly integrate ringless voicemail delivery into your software. Successful deliveries are deducted from your account balance based on the rate dictated by your monthly subscription plan. Invoke the Drop Cowboy API from your application by sending an HTTP POST containing a json document with the attributes listed below. Once delivery is attempted, you will receive a callback containing the delivery status to the webhook you specified in your API settings contained in your account.

Authorizations

x-team-id / x-secretstringRequired

Requires two headers: x-team-id and x-secret. Both must be sent with each request.

Body

team_idstring · enumRequired

Located on the API Setting tab. (Required)

Possible values:

secretstring · enumRequired

Located on the API Setting tab. (Required)

Possible values:

foreign_idstring · enumRequired

A value to identify this drop in your system. Will be passed through to you in the webhook callback. Max length 256 characters. (Required)

Possible values:

brand_idstring · enumRequired

Located on in your account's trust center tab. (Required)

Possible values:

phone_numberstring · enumRequired

Your contact's phone number in E.164 format. (Required)

Possible values:

recording_idstring · enumOptional

The ID of the audio recording to send to your contacts. Located on in your account's recordings tab. *Not required if you are using audio_url or voice_id

Possible values:

voice_idstring · enumOptional

The ID of the Mimic AITM voice to use when reading your tts_body. Located on in your account's voices tab. *Not required if you are audio_url or recording_id. Must use in conjunction with tts_body.

Possible values:

tts_bodystring · enumOptional

The text you want Mimic AITM to convert to speech using the voice_id you specify. *Required if using voice_id

Possible values:

audio_urlstring · enumOptional

Use of this property requires special approval. Please contact support. | A url to the voicemail audio to play (mp3 or wav). *Not required if you are using recording_id or voice_id

Possible values:

audio_typestring · enumOptional

Use of this property requires special approval. Please contact support.

Possible values:

forwarding_numberstring · enumOptional

The phone number to forward calls and texts to when the contact replies to your message. Must be in E.164 format.

Possible values:

phone_ivr_idstring · enumOptional

The IVR to use when your contact calls you back. Located on in your account's phone ivr tab.

Possible values:

pool_idstring · enumOptional

The ID of the private number pool to select phone numbers from based on geographic location of your contact.

Possible values:

postal_codestring · enumOptional

The zip code / postal code of your contact. Supplying a value for postal code is optional but provides more accurate compliance with TCPA calling hours.

Possible values:

callback_urlstring · enumOptional

Override the default RVM webhook url that you specified in your API settings.

Possible values:

byocobject · enumOptional

Wholesale customers are able to specify SIP Trunks and STIR/SHAKEN credentials.

Possible values:

Responses

200

Request accepted. Delivery status delivered via webhook callback.

application/json

post

/rvm

POST /v1/rvm HTTP/1.1
Host: api.dropcowboy.com
x-team-id / x-secret: YOUR_API_KEY
Content-Type: application/json
Accept: */*
Content-Length: 520

{
  "team_id": "<Your Account>",
  "secret": "<Your Secret>",
  "foreign_id": "<Your system's ID>",
  "brand_id": "<Your Brand GUID>",
  "phone_number": 15552223333,
  "recording_id": "<Your Recording GUID>",
  "voice_id": "<Your Voice GUID>",
  "tts_body": "Hey Joe",
  "audio_url": "https://example.com/your-file.mp3",
  "audio_type": "mp3",
  "forwarding_number": 15557778888,
  "phone_ivr_id": "<Your IVR GUID>",
  "pool_id": "Defaults to the public pool of shared numbers",
  "postal_code": 2101,
  "callback_url": "http://example.com",
  "byoc": "Please contact us for details"
}

200

Request accepted. Delivery status delivered via webhook callback.

{
  "status": "text"
}

Example Request (static audio file hosted on Drop Cowboy platform)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	"brand_id": "00000000-0000-0000-0000-000000000000", 
 	"recording_id": "00000000-0000-0000-0000-000000000000", 
 	"phone_number": "+15552223333", 
 	"forwarding_number": "+15557778888", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com"
}'

Example Request (static audio file hosted on your servers)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	"brand_id": "00000000-0000-0000-0000-000000000000", 
 	"audio_url": "https://your.server.com/audio.mp3", 
 	"audio_format": "mp3", 
 	"phone_number": "+15552223333", 
 	"forwarding_number": "+15557778888", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com" 
}'

Example Request (private number pool)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	"brand_id": "00000000-0000-0000-0000-000000000000", 
 	"recording_id": "00000000-0000-0000-0000-000000000000", 
 	"phone_number": "+15552223333", 
 	"pool_id": "00000000-0000-0000-0000-000000000000", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com" 
}'

Example Request (specific caller ID)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	"brand_id": "00000000-0000-0000-0000-000000000000", 
 	"recording_id": "00000000-0000-0000-0000-000000000000", 
 	"phone_number": "+15552223333", 
 	"caller_id": "+15557778888", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com" 
}'

Example Request (privacy enabled, display Unknown Caller as caller ID)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	"brand_id": "00000000-0000-0000-0000-000000000000", 
 	"recording_id": "00000000-0000-0000-0000-000000000000",
   	"phone_number": "+15552223333", 
 	"caller_id": "+15557778888", 
 	"privacy": "full", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com" 
}'

Example Request (generative AI text to speech)

curl --location 'https://api.dropcowboy.com/v1/rvm' \ 
--header 'Content-Type: application/json' \ 
--data '{ 
 	"team_id": "TEAM_ID", 
 	"secret": "SECRET", 
 	  "brand_id": "00000000-0000-0000-0000-000000000000", 
 	"voice_id": "00000000-0000-0000-0000-000000000000", 
 	"tts_body": "Hello World!", 
 	"phone_number": "+15552223333", 
 	"caller_id": "+15557778888", 
 	"foreign_id": "YOUR_DATABASE_RECORD_ID", 
 	"callback_url": "https://your.server.com" 
}'

Example Response

{ 
    "status": "queued" 
}

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